Inner diameter shroud assembly for variable inlet guide vane structure in a gas turbine engine

ABSTRACT

An inner shroud assembly includes an aft core segment mountable to a forward core segment to support a multiple of vanes for rotational movement relative thereto. A shroud backing plate segment engageable with the aft core segment and at least one fastener which passes through the shroud backing plate, the aft core segment and the forward core segment.

RELATED APPLICATION

This application is a continuation of U.S. Ser. No. 12/478,955, whichwas filed on Jun. 5, 2009.

BACKGROUND

The present disclosure relates to a gas turbine engine and moreparticularly to an inner diameter shroud assembly for a variable inletguide vane structure.

Gas turbine engines generally include a high pressure compressor, acombustor, and a high pressure turbine. The high pressure compressor,combustor, and high pressure turbine may be collectively referred to asthe core of an engine. Such gas turbine engines also may include a lowpressure compressor for supplying compressed air, for furthercompression, to the high pressure compressor.

The low pressure compressor typically includes a rotor surrounded by acasing. The casing is typically fabricated to be removable, such as byforming the casing into portions that are removably joined together. Thelow pressure compressor includes a plurality of stages and each stageincludes a row of rotor blades and a row of stator vanes. The casingsupports the stator vanes, and the rotor supports the rotor blades. Thestator vane rows typically direct air flow toward a downstream rotorblade row.

Several compressor stator vanes may be rotatively mounted to allow eachvane to rotate around a longitudinal axis which extends in a radialdirection from the centerline of the engine to adjust the angularorientation of the vane relative to the airflow. These variable statorvane assemblies facilitate control of air flow through the compressor toenhance performance of the compressor.

Integration of the variable stator vane assemblies into the casing maybe relatively complicated. Furthermore, assembly modularity of variouscase design philosophies such as ring-case and split-case arrangementsmay need to be accommodated.

SUMMARY

An inner shroud assembly according to an exemplary aspect of the presentdisclosure includes an aft core segment mountable to a forward coresegment to support a multiple of vanes for rotational movement. A shroudbacking plate segment engageable with the aft core segment and at leastone fastener which passes through the shroud backing plate to retain theaft core segment to the forward core segment.

An inner shroud assembly according to an exemplary aspect of the presentdisclosure includes an aft core segment mountable to a forward coresegment to support a multiple of vanes for rotational movement. A shroudbacking plate segment engageable with the aft core segment. A fastenerretainer mountable to the shroud backing plate segment. At least onefastener receipt member mountable within the aft core segment and theforward core segment, the at least one fastener receipt member spans theaft core segment and the forward core segment. A fastener which passesthrough the fastener retainer and the shroud backing plate to retain theaft core segment to the forward core segment.

An inner shroud assembly according to an exemplary aspect of the presentdisclosure includes an aft core segment mountable to a forward coresegment to support a multiple of vanes for rotational movement. A shroudbacking plate segment engageable with the aft core segment, the shroudbacking plate defines an aft segment perpendicular to a base segment,the base segment at least partially spans the aft core segment and theforward core segment. At least one alignment member mountable within theaft core segment and the forward core segment. At least one fastenerreceipt member mountable within the shroud backing plate and a fastenerwhich passes through said fastener receipt member to retain the aft coresegment to the forward core segment.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features will become apparent to those skilled in the art fromthe following detailed description of the disclosed non-limitingembodiment. The drawings that accompany the detailed description can bebriefly described as follows:

FIG. 1 is a general schematic sectional view through a gas turbineengine along the engine longitudinal axis;

FIG. 2 is a expanded schematic sectional view through a low pressurecompressor section of the gas turbine engine illustrating one embodimentof an inner shroud assembly;

FIG. 3 is an exploded view of the inner shroud assembly viewed from anaft perspective thereof;

FIG. 4 is an exploded view of a forward core segment and an aft coresegment from an aft perspective thereof;

FIG. 5 is an exploded view of the forward core segment and the aft coresegment from a top perspective thereof;

FIG. 6 is a perspective sectional view of the inner shroud assemblyviewed from an aft perspective thereof attached to a forward center bodyengine casing;

FIG. 7 is a longitudinal sectional view of the inner shroud assemblyattached to the forward center body engine casing;

FIG. 8 is a perspective view of a shroud backing plate segment;

FIG. 9 is a perspective view of a fastener retainer segment;

FIG. 10 is an expanded sectional view of the inner shroud assembly ofFIG. 10;

FIG. 11 is an exploded view of the inner shroud assembly of FIG. 10viewed from an outer perspective thereof;

FIG. 12 is a sectional view of the inner shroud assembly of FIG. 10;

FIG. 13 is a perspective sectional view of the inner shroud assembly ofFIG. 10 attached to the Number-2 Bearing Support Housing;

FIG. 14 is a perspective view of the inner shroud assembly of FIG. 10which illustrates an anti-rotation pad;

FIG. 15 is a perspective view of a fastener retainer which includes tabsin an unengaged position to receive a tool to tighten/loosen thefastener;

FIG. 16 is a perspective view of a fastener retainer which includes tabsin an engaged position;

FIG. 17 is a perspective partial sectional view of the inner shroudassembly of FIG. 10; and

FIG. 18 is a partially assembled view of the inner shroud assembly ofFIG. 10 viewed from a rearward perspective thereof.

DETAILED DESCRIPTION

FIG. 1 illustrates a general schematic view of a gas turbine engine 10such as a gas turbine engine for propulsion. While a two spool highbypass turbofan engine is schematically illustrated in the disclosednon-limiting embodiment, it should be understood that the disclosure isapplicable to other gas turbine engine configurations, including, forexample, gas turbines for power generation, turbojet engines, low bypassturbofan engines, turboshaft engines, etc.

The engine 10 includes a core engine section that houses a low spool 14and high spool 24. The low spool 14 includes a low pressure compressor16 and a low pressure turbine 18. The core engine section drives a fansection 20 connected to the low spool 14 either directly or through agear train. The high spool 24 includes a high pressure compressor 26 andhigh pressure turbine 28. A combustor 30 is arranged between the highpressure compressor 26 and high pressure turbine 28. The low and highspools 14, 24 rotate about an engine axis of rotation A.

Air compressed in the compressor 16, 26 is mixed with fuel, burned inthe combustor 30, and expanded in turbines 18, 28. The air compressed inthe compressors 16, 26 and the fuel mixture expanded in the turbines 18,28 may be referred to as a hot gas stream along a core gas path. Theturbines 18, 28, in response to the expansion, drive the compressors 16,26 and fan section 20.

Referring to FIG. 2, the low pressure compressor 16 includes alternaterows of low pressure compressor rotor blades 40 mountable to disks 42which at least partially define a rotor stage. A multiple of variableinlet guide vanes 44 facilitate direction of the airflow from a frontcenter body 32 into the low pressure compressor rotor blades 40.

An outer shroud 46, which may also be referred to as a ring case,secures an outer trunion 48 of each variable vane 44. The outer trunion48 is driven to pivot by a linkage 50 connected to an actuator 52.

An inner shroud assembly 60 secures an inner trunion 62 of each variablevane 44 for pivotal movement. It should be understood that although thefront center body 32 is disclosed as the static structure to which theinner shroud assembly 60 is attached in the disclosed, non-limitingembodiment, the inner shroud assembly 60 may be mounted to other staticstructures.

The variable vane 44 can be caused to pivot through operation of theactuator 52 and linkage 50 in response to operational conditions tocontrol the direction of air delivered from one compressor stage to thedownstream compressor stage. The times when such pivotal movement isdesirable are within the level or ordinary skill in the art. Thisdisclosure relates to an inner shroud assembly 60, and not the movementof the vane 44 itself. Although a particular variable inlet guide vane44 stage is illustrated in the disclosed non-limiting embodiment, itshould be understood that any variable vane structure may benefitherefrom.

Referring to FIG. 3, the inner shroud assembly 60 generally includes amultiple of forward core segments 64, a multiple of aft core segments66, a multiple of shroud backing plate segments 68, a multiple offastener retainers 70, a multiple of fasteners 72 and a multiple offastener receipt members 74.

The forward core segments 64 and the aft core segments 66 in thedisclosed, non-limiting embodiment are manufactured of a compositematerial and define an arcuate segment of approximately sixty degrees.Each of the forward core segments 64 and the aft core segments 66 havecorresponding outer support surfaces 76A, 76B which are part-cylindricalto receive a platform 44P of the vane 44 (FIGS. 4 and 5). Respectivecorresponding part-cylindrical inner support surfaces 80A, 80B supportan extended diameter portion 44D of the inner trunion 62 with a reduceddiameter part-cylindrical center portion 78A, 78B located between theouter support surfaces 76A, 76B and the inner support surfaces 80A, 80Bto capture an intermediate portion 44T of the inner trunion 62. Itshould be understood that the forward core segments 64 and the aft coresegments 66 may define alternative support structures to support aninner trunion of other configurations and designs.

The forward core segments 64 and the aft core segments 66 includealignment apertures 84A (FIG. 4 from 84B to 84A), 84B each of whichreceive a fastener receipt member 74 therein. As the forward coresegments 64 and the aft core segments 66 may be manufactured of acomposite material, the fastener receipt members 74 may be manufacturedof a metallic material to protect the forward core segments 64 and theaft core segments 66 from the fasteners 72 which pass therethrough toengage the front center body 32 (FIG. 6). The fastener receipt members74 facilitate alignment and prevent relative rotation between theforward core segments 64 and the aft core segments 66. The fastenerreceipt members 74 also operate as standoffs to prevent compression ofthe forward core segments 64 and the aft core segments 66 when thefasteners 72 are tightened into the front center body 32.

The forward core segments 64 also define a circumferentiallyintermittent interface surface 86 (FIG. 5) which locks the forward coresegments 64 into the front center body 32 which includes a correspondingintermittent interface surface (FIG. 7).

Each of the multiple of shroud backing plate segments 68 in thedisclosed, non-limiting embodiment are manufactured of a metallicmaterial such as aluminum and define an arcuate segment of approximatelyone hundred and eighty degrees. (also illustrated in FIG. 8) Each of themultiple of shroud backing plate segments 68 supports the forward coresegments 64 and the aft core segments 66 and include apertures 88 whichalign with apertures 84.

Each of the multiple of fastener retainers 70 in the disclosed,non-limiting embodiment are manufactured of a metallic material such asInconel 625 or Nickel Alloy and define an arcuate segment ofapproximately one hundred and eighty degrees for receipt into the shroudbacking plate segments 68 (also illustrated in FIG. 9). Each of themultiple of fastener retainers 70 are keyed to the adjacent shroudbacking plate segments and include apertures 90 which align withapertures 88 and 84 (FIGS. 6 and 7). The multiple of fastener retainers70 prevent gas impingement onto the heads of the fasteners 72 to provideprotection therefrom. The multiple of fastener retainers 70 also lockthe fasteners 72 to prevent rotation thereof and thereby providetertiary retention, fastener abrasion protection and galvanicprotection.

Referring to FIG. 10, another non-limiting embodiment of an inner shroudassembly 100 generally includes a multiple of forward core segments 102,a multiple of aft core segments 104, a multiple of shroud backing platesegments 106A, 106B, a multiple of alignment members 108, a multiple offasteners 110 a multiple of fastener retainers 112, a multiple offastener receivers 114, and a multiple of fastener receipt members 116.

The forward core segments 102 and the aft core segments 104 in thedisclosed, non-limiting embodiment are manufactured of a compositematerial and define an arcuate segment of approximately sixty degreesgenerally as described above.

The forward core segments 102 and the aft core segments 104 definealignment apertures 118A, 118B which receive the alignment members 108therein (FIG. 11). The alignment members 108 include a central increaseddiameter section 108A controlling the depth to which the pin isinstalled and circumferentially aligns 76A and 76B of leading andTrailing Composite Segments 102 and 104 respectively. Alignment member108 provides Structural Circumferential and Radial alignment of CoreSegments 102 and 104 and additionally enhances production assembly. Inthis non-limiting embodiment, the multiple of fasteners 110 are separatefrom the multiple of alignment members 108.

Each of the multiple of shroud backing plate segments 106A, 106B in thisnon-limiting embodiment are manufactured of a metallic material such asaluminum and define an arcuate segment of approximately one hundred andeighty degrees (also illustrated in FIG. 12). Each of the multiple ofshroud backing plate segments 106A, 106B supports the respective forwardcore segments 102 and the aft core segments 104 and includes apertures120 which receive the fastener receivers 114.

Referring to FIG. 12, the shroud backing plate segments 106A abut thefront center body 32 to capture and protect the forward core segments102. The shroud backing plate segments 106B operates to capture andprotect the aft core segments 104. The shroud backing plate segments106A, 106B may include a respective lip 106C, 106D which captures anupper surface of the forward core segments 102 and the aft core segments104. Additionally, 106C and 106D minimize non-metallic surfaces ofcomposite segments 102 and 104 Exposed to the ID-Flow Path 51.

Referring to FIG. 13, an anti-rotation pad 132 extends radially inwardfrom the forward core segments 102 to engage with an anti-rotationrecessed area 134 within the shroud backing plate segment 106A (alsoillustrated in FIG. 5). The anti-rotation pad 132 and the anti-rotationrecessed area 134 operates as n anti-rotation feature as the fasteners110 extend through the multiple of fastener receipt members 116 which donot pass through the forward core segments 102 and the aft core segment104 as in the above discussed non-limiting embodiment (FIG. 14).

The aft shroud backing plate segment 106B includes a recessed area 128about each aperture 120 to receive the fastener retainer 112 therein.The recessed area 128 essentially follows the outer profile of thefastener retainer 112.

The fastener retainer 112 includes tabs 130 which engage the flange, hexor double hex fastener 110 to prevent rotation thereof and therebyprovide a fastener rotation prevention mechanism which uniquelyaccommodates the flanges of double hex head configured bolt fasteners. Aloose fastener 110 will essentially rotate the fastener retainer 112into the recessed area 128 which operates as a rotation stop to preventfurther loosening of the fastener 110.

The tabs 130 initially provide space to receive a fastener tool whichengages the fastener 110 (FIG. 15). Once the fastener 110 is properlytightened, the tabs 30 may be bent into engagement with the fastenerhead 110H (FIG. 16).

The tabs 30 also serve to retain the bolt head 110H if unforeseenfractures occur from either fatigue or assembly, Achieve TertiaryRetention. The fastener retainer 112 further provides fastener abrasionprotection and galvanic protection (FIGS. 17 and 18).

It should be understood that relative positional terms such as“forward,” “aft,” “upper,” “lower,” “above,” “below,” and the like arewith reference to the normal operational attitude of the vehicle andshould not be considered otherwise limiting.

It should be understood that like reference numerals identifycorresponding or similar elements throughout the several drawings. Itshould also be understood that although a particular componentarrangement is disclosed in the illustrated embodiment, otherarrangements will benefit herefrom.

Although particular step sequences are shown, described, and claimed, itshould be understood that steps may be performed in any order, separatedor combined unless otherwise indicated and will still benefit from thepresent disclosure.

The foregoing description is exemplary rather than defined by thelimitations within. Various non-limiting embodiments are disclosedherein, however, one of ordinary skill in the art would recognize thatvarious modifications and variations in light of the above teachingswill fall within the scope of the appended claims. It is therefore to beunderstood that within the scope of the appended claims, the disclosuremay be practiced other than as specifically described. For that reasonthe appended claims should be studied to determine true scope andcontent.

1. An inner shroud assembly comprising: a forward core segment; an aftcore segment mountable to said forward core segment to support amultiple of vanes for rotational movement; a shroud backing platesegment engageable with said aft core segment; and at least one fastenerwhich passes through said shroud backing plate to retain said aft coresegment to said forward core segment. At least one fastener receiptmember mounted within said aft core segment and said forward coresegment wherein said fastener receipt member limits compression uponsaid forward core segment and said aft core segment if said one fasteneris tightened.
 2. The assembly as recited in claim 1, wherein said atleast one fastener receipt member spans said aft core segment andforward core segment.
 3. The assembly as recited in claim 1, whereinsaid aft core segment and said forward core segment are manufactured ofa non-metallic material.
 3. The assembly as recited in claim 1, whereineach of said at least one fastener passes through said fastener receiptmember, said at least one fastener receipt member is a metallic tubularmember.
 4. The assembly as recited in claim 1, further comprising afastener retainer mountable to said shroud backing plate segment, saidfastener retainer operable to lock said at least one fastener.
 5. Theassembly as recited in claim 1, wherein a fastener retainer defines anarcuate segment of approximately one hundred and eighty degrees.
 6. Theassembly as recited in claim 7, wherein said fastener retainer ismanufactured of a metallic material.
 7. The assembly as recited in claim8, wherein said fastener retainer is manufactured of Inconel
 625. 8. Theassembly as recited in claim 1, further comprising a fastener retainermountable to said shroud backing plate segment, said fastener retainerincludes tabs operable to lock said at least one fastener.
 9. Theassembly as recited in claim 10, wherein said fastener retainer includesan arcuate surface opposite said tabs.
 10. The assembly as recited inclaim 10, wherein an outer surface of an aft segment of said shroudbacking plate segment defines a recessed area which follows an outerprofile of said fastener retainer.
 11. The inner shroud assembly ofclaim 1 further comprising: one of said forward core segment and saidaft core segment having an internal shoulder for receiving said end ofsaid at least one fastener receipt member wherein said fastener receiptmember limits compression upon said forward core segment and said aftcore segment if said one fastener is tightened.